Solid element devices comprising a solid element, such as a light emitting diode, sealed with a light transparent resin material such as an epoxy resin have hitherto been known. In such solid element devices, it is known that, upon exposure to high intensity light, the light transparent resin causes deterioration such as yellowing. In particular, when a group III nitride-based compound semiconductor light emitting element which emits short-wavelength light is used, the light transparent resin near the element is yellowed by high energy light generated from the element and the heat generated from the element per se and, consequently, the light takeout efficiency is often lowered to an extent that is not negligible.
In order to prevent the deterioration of the sealing member, a luminescent device using a low melting glass as a sealing member, has been proposed in Japanese Patent Laid-Open Nos. 1996-102553 and 1999-177129.
In the luminescent device described in Japanese Patent Laid-Open No. 1996-102553, an LED element, a wire bonding part, and the periphery of the upper end of a lead part are covered with a sealing body 7 made of a transparent low melting glass. The low melting glass used is that, for example, selenium, thallium, arsenic, or sulfur has been added to bring the melting point to about 130 to 350° C. In this case, preferably, the low melting glass has a melting point of 200° C. or below (more preferably 150° C. or below).
According to the luminescent device described in Japanese Patent Laid-Open No. 1996-102553, a problem of a change in color of the sealing body to yellow with the elapse of time due to poor or weak resistance to ultraviolet light possessed by the epoxy resin and the like can be avoided.
On the other hand, the luminescent device described in Japanese Patent Laid-Open No. 1999-177129 uses, as a sealing body covering the LED light emitting element, a low melting glass having a refractive index of about 2 which is close to the refractive index of a GaN-based LED light emitting element, about 2.3.
According to the luminescent device described in Japanese Patent Laid-Open No. 1999-177129, sealing of the LED light emitting element with the low melting glass having a refractive index close to the GaN-based LED light emitting element can reduce the quantity of light, which is totally reflected from the surface of the LED light emitting element and is returned to the inside, and can increase the quantity of light, which is emitted from the LED light emitting element and enters the low melting glass. As a result, the emission efficiency of the chip-type LED and the like according to the invention of the application is higher than the conventional device in which the LED light emitting element has been sealed with the epoxy resin.
According to the solid element devices using the conventional low melting glass as the sealing member, although the glass is low melting glass, high temperature fabrication should be carried out, and, due to the hard material, in fact, disadvantageously, any sample device cannot be provided by the continuation of the resin sealing.
Accordingly, an object of the invention is to extract and solve problems involved in the realization of inorganic material sealing and to provide a solid element device, which can actually offer expected effects by glass sealing, and a method for manufacturing the same.